1. Field of the Invention
Embodiments of this invention relate to a capacitive type touch screen panel.
2. Discussion of the Related Art
Along with the development of the electronics industry, display devices, such as a liquid crystal display, an electroluminescent display, and a plasma display panel having a quick response speed, low power consumption, and an excellent color reproduction rate, have been in the spotlight. The display device is used for various electronic products such as a television, a monitor for a computer, a notebook computer, a mobile phone, a display unit of a refrigerator, a personal digital assistant, and an automated teller machine. In general, the display device interfaces with various input devices such as a keyboard, a mouse, and a digitizer. However, when a separate input device such as a keyboard, a mouse a digitizer is used, a user is required to know how to use the separate input device, and as the separate input device occupies space, the display device that is separate from the various input devices is inconvenient in view of customer satisfaction. Therefore, need for a convenient and simple input device that can reduce erroneous operation has gradually increased. According to such request a touch screen panel in which a user can input information by directly contacting with a screen by a finger or a pen is suggested.
Because the touch screen panel has a simple configuration while occurring little or no erroneous operations, can perform an input action without a separate input device, and has convenience in which the user can quickly and easily manipulate through contents displayed on a screen, the touch screen panel is applied to various display devices.
Touch screen panels are classified into a resistive type, a capacitive type, an electromagnetic type and so on according to a detection method of a touched portion. The resistive type touch screen panel determines a touched position by a voltage gradient according to resistance in a state that a DC voltage is applied to metal electrodes formed on an upper plate or a lower plate. The capacitive type touch screen panel senses a touched position according to a difference in capacitance created in an upper or lower plate when the user physically contacts with a conductive film formed on the upper or lower plate. The electromagnetic type touch screen panel detects a touched portion by reading an LC value induced as an electromagnetic pen touches a conductive film.
Hereinafter, a conventional capacitive type touch screen panel will be described with reference to FIGS. 1 and 2. FIG. 1 is a top plan view illustrating a conventional capacitive type touch screen panel, and FIG. 2 is a cross-sectional view illustrating the touch screen panel taken along line I-I′ and line II-II′ of FIG. 1.
Referring to FIGS. 1 and 2, the conventional capacitive type touch screen panel includes an electrode forming part 20, a routing wire forming part 40, a pad part 60, and a protective layer 50.
The electrode forming part 20 is formed on a substrate 10 and includes a plurality of first electrodes 21 arranged in parallel in a first direction (for example, an X-axis direction) and a plurality of second electrodes 22 arranged to intersect in a direction (for example, an Y-axis direction) perpendicular to the first electrodes 21. The first electrodes 21 and the second electrodes 22 intersect each other, but sustain an electrical insulation state by an insulation film 30. Further, neighboring first electrodes 21 arranged in the first direction are connected to each other by a bridge 41. That is, the bridge 41 connects the neighboring first electrodes 21 to each other through contact holes 30a and 30b formed in the insulation film 30 covering the first and second electrodes 21 and 22.
The routing wire forming part 40 is formed on the substrate 10 at positions outside the electrode forming part 20 and includes a plurality of first routing wires 42 connected to the plurality of first electrodes 21, respectively, and a plurality of second routing wires 43 connected to the plurality of second electrodes 22, respectively.
The pad part 60 includes a plurality of first pads connected to the plurality of first electrodes 21 through the plurality of first routing wires 42, respectively, and a plurality of second pads 62 connected to the plurality of second electrodes 22 through the plurality of second routing wires 43, respectively.
The protective layer 50 covers the electrode forming part 20 and the routing wire forming part 40 and prevents the first and second electrodes 21 and 22 and the first and second routing wires 42 and 43 from being exposed to the outside.
Hereinafter, a method of manufacturing a conventional capacitive type touch screen panel will be described with reference to FIGS. 3A to 3D.
Referring to FIG. 3A, a first conductive layer for forming first and second electrodes is deposited on the substrate 10 including an electrode forming part 20, a routing wire forming part 40, and the pad part 60 through a deposition process such as a sputtering method. As the first conductive layer, an indium tin oxide (ITO) layer is generally used. After a photoresist is coated on the substrate 10 in which the first conductive layer is formed, a first photoresist pattern for exposing the first conductive layer is formed in the electrode forming part 20 by performing a photolithography process using a first mask. After removing the first conductive layer exposed by the first photoresist pattern through wet etching, a plurality of first electrodes 21 and a plurality of second electrodes 22 intersecting the first electrodes 21 are formed on the substrate 10 by ashing the remaining first photoresist pattern.
Referring to FIG. 3B, after the first insulation film 30 is formed on the substrate 10 in which the plurality of first and second electrodes 21 and 22 are formed, the first insulation film 30 of the pad part 60 and the routing wire forming part 40 is removed and first and second contact holes 30a and 30b penetrating the first insulation film 30 of the electrode 20 are formed with a photolithography process and an etching process using a second mask. The first and second contact holes 30a and 30b expose a portion of the neighboring first electrodes 21. The first insulation film 30 includes silicon nitride, silicon oxide, or organic resin.
Referring to FIG. 3C, a second conductive layer is formed on an entire surface of the substrate 10 in which the first and second contact holes 30a and 30b are formed through a deposition process such as a sputtering method. The second conductive layer includes aluminum (Al) or molybdenum (Mo). After coating a photoresist on the substrate in which the second conductive layer is formed, first and second routing wires 42 and 43 are formed in a routing wire forming portion on the substrate 10 and a connection electrode 41 is formed on the first insulation film 30 of the electrode forming part 20 by performing a photolithography process and an etching process using a third mask. The connection electrode 41 connects the neighboring first electrodes 21 to each other through the first and second contact holes 30a and 30b formed in the first insulation film 30.
Referring to FIG. 3D, after a second insulation film 50 as a protective film is formed on an entire surface of the substrate 10 in which the connection electrode 41 and the first and second routing wires 42 and 43 are formed, a through hole 50a for penetrating the second insulation film 50 is formed to expose the first and second routing wires 42 and 43 of the pad 60 with a photolithography process and an etching process using a fourth mask.
However, the conventional capacitive type touch screen panel is manufactured with 4 mask processes, as described above, and each mask process accompanies a photolithography process requiring a series of continuous processes such as photoresist (PR), coating, alignment, exposure, development, and cleaning and thus it is necessary to reduce a number of a mask process. Further, because the first insulation film of an intersecting portion of the first electrode and the second electrode has a wide area and uses silicon nitride, silicon oxide, and organic resin, there is a problem that the first insulation film is viewed or apparent from the outside due to a color difference between the first insulation film and a periphery thereof. Further, the second insulation film formed as a protective film at the top of the touch screen panel is made of the same material as that of the first insulation film, and adhesive strength is weakened by gas used when depositing the first and second insulation films and thus surface hardness is weakened. Therefore, after a touch screen panel is manufactured, when a next process of forming a display device is performed, an additional problem of a scratch occurs. FIG. 4 is a drawing illustrating states before and after performing a scratch test of the touch screen panel manufactured in the related art, wherein the left picture illustrates a state before a scratch test and the right picture illustrates a state after a scratch test.